<form class="form-group article-search col-md-8 col-xs-10" (ngSubmit)="search(keyword)">
  <label class="control-label" for="keyword">关键字:</label>
  <div class="search-group input-group">
    <input id="keyword" name="keyword" type="text" class="form-control" [(ngModel)]='keyword'
           (keydown.enter)="search(keyword)"
           placeholder="title, tag, article..."/>
    <button type="submit" class="search-btn btn btn-primary" name="keyword">
      <i class="fa fa-search" aria-hidden="true"></i>查询
    </button>
  </div>
</form>
